我遇到了mysql服务器的一些问题当我运行top命令时，可以看出mysql进程占用了350-500％的CPU 我用49 GB RAM运行centos 6
my.cnf设置：
[mysqld]
# delayed_insert_timeout=20
net_write_timeout=60
#slow_query_log_file = /var/lib/mysql/mysqld_slow_queries.log
#long_query_time=10
#general_log = on
key_buffer=4024M
open_files_limit=154378
innodb_buffer_pool_size=4G
key_buffer_size=4G
query_cache_min_res_unit=7096
max_connections=100000
sort_buffer_size=100M
myisam_sort_buffer_size=128M
tmp_table_size=5042M
table_definition_cache=4000
innodb_additional_mem_pool_size=100M
default-storage-engine=MyISAM
read_buffer_size=100M
thread_cache_size=2042M
query_cache_size=2084M
join_buffer_size=100M
innodb_thread_concurrency=12
max_heap_table_size=5042M
net_read_timeout=60
max_allowed_packet=560M
query_cache_type=1
read_rnd_buffer_size=100M
innodb_flush_method=O_DIRECT
wait_timeout=60
innodb_file_per_table=1
skip-name-resolve
query_cache_limit=100M
table_open_cache=1000
interactive_timeout=9
[mysql]
#wait_timeout=15
#net_read_timeout=40
no-auto-rehash
#interactive_timeout=15
[mysql_safe]
log_error="/var/log/mysqld.log"
#wait_timeout=15
#net_read_timeout=40
#interactive_timeout=15
open-files-limit=154378
skip-name-resolve
[mysqlhotcopy]
#interactive-timeout=15
MySQLTuner的输出：
>> MySQLTuner 1.7.1 - Major Hayden <major@mhtx.net>
>> Bug reports, feature requests, and downloads at http://mysqltuner.com/
>> Run with '--help' for additional options and output filtering
[--] Skipped version check for MySQLTuner script
[!!] Currently running unsupported MySQL version 10.0.30-MariaDB
[OK] Operating on 64-bit architecture
-------- Log file Recommendations ------------------------------------------------------------------
[--] Log file: /var/lib/mysql/xx.xx.com.err(177K)
[OK] Log file /var/lib/mysql/xx.xx.com.err exists
[OK] Log file /var/lib/mysql/xx.xx.com.err is readable.
[OK] Log file /var/lib/mysql/xx.xx.com.err is not empty
[OK] Log file /var/lib/mysql/xx.xx.com.err is smaller than 32 Mb
[!!] /var/lib/mysql/xx.xx.com.err contains 618 warning(s).
[!!] /var/lib/mysql/xx.xx.com.err contains 69 error(s).
[--] 44 start(s) detected in /var/lib/mysql/xx.xx.com.err
[--] 1) 170416 3:05:14 [Note] /usr/sbin/mysqld: ready for connections.
[--] 2) 170416 0:28:36 [Note] /usr/sbin/mysqld: ready for connections.
[--] 3) 170416 0:23:34 [Note] /usr/sbin/mysqld: ready for connections.
[--] 4) 170415 11:49:57 [Note] /usr/sbin/mysqld: ready for connections.
[--] 5) 170415 9:25:33 [Note] /usr/sbin/mysqld: ready for connections.
[--] 6) 170413 23:17:07 [Note] /usr/sbin/mysqld: ready for connections.
[--] 7) 170413 21:54:37 [Note] /usr/sbin/mysqld: ready for connections.
[--] 8) 170406 11:14:35 [Note] /usr/sbin/mysqld: ready for connections.
[--] 9) 170402 18:11:05 [Note] /usr/sbin/mysqld: ready for connections.
[--] 10) 170402 18:00:51 [Note] /usr/sbin/mysqld: ready for connections.
[--] 40 shutdown(s) detected in /var/lib/mysql/xx.xx.com.err
[--] 1) 170416 3:05:11 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 2) 170416 0:28:34 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 3) 170416 0:23:31 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 4) 170415 11:49:55 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 5) 170415 9:24:08 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 6) 170413 23:17:05 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 7) 170413 21:53:09 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 8) 170406 11:13:06 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 9) 170402 18:11:03 [Note] /usr/sbin/mysqld: Shutdown complete
[--] 10) 170402 18:00:50 [Note] /usr/sbin/mysqld: Shutdown complete
-------- Storage Engine Statistics -----------------------------------------------------------------
[--] Status: +ARCHIVE +Aria +BLACKHOLE +CSV +FEDERATED +InnoDB +MEMORY +MRG_MyISAM +MyISAM +PERFORMANCE_SCHEMA
[--] Data in MyISAM tables: 7G (Tables: 221)
[--] Data in InnoDB tables: 480K (Tables: 14)
[--] Data in MEMORY tables: 0B (Tables: 1)
[OK] Total fragmented tables: 0
-------- Security Recommendations ------------------------------------------------------------------
[OK] There are no anonymous accounts for any database users
[OK] All database users have passwords assigned
[!!] There is no basic password file list!
-------- CVE Security Recommendations --------------------------------------------------------------
[--] Skipped due to --cvefile option undefined
-------- Performance Metrics -----------------------------------------------------------------------
[--] Up for: 23h 32m 29s (480M q [5K qps], 10M conn, TX: 322G, RX: 18G)
[--] Reads / Writes: 99% / 1%
[--] Binary logging is disabled
[--] Physical Memory : 47.3G
[--] Max MySQL memory : 39105.2G
[--] Other process memory: 22.7G
[--] Total buffers: 15.2G global + 400.3M per thread (100000 max threads)
[--] P_S Max memory usage: 0B
[--] Galera GCache Max memory usage: 0B
[!!] Maximum reached memory usage: 333.8G (706.29% of installed RAM)
[!!] Maximum possible memory usage: 39105.2G (82749.33% of installed RAM)
[!!] Overall possible memory usage with other process exceeded memory
[OK] Slow queries: 0% (439/480M)
[OK] Highest usage of available connections: 0% (815/100000)
[OK] Aborted connections: 0.00% (40/10747826)
[!!] Query cache may be disabled by default due to mutex contention.
[OK] Query cache efficiency: 49.8% (433M cached / 871M selects)
[OK] Query cache prunes per day: 0
[OK] Sorts requiring temporary tables: 0% (0 temp sorts / 219K sorts)
[OK] No joins without indexes
[!!] Temporary tables created on disk: 41% (726 on disk / 1K total)
[OK] Thread cache hit rate: 99% (815 created / 10M connections)
[OK] Table cache hit rate: 96% (691 open / 713 opened)
[OK] Open file limit used: 0% (870/500K)
[OK] Table locks acquired immediately: 99% (3M immediate / 3M locks)
-------- Performance schema ------------------------------------------------------------------------
[--] Performance schema is disabled.
[--] Memory used by P_S: 0B
[--] Sys schema isn't installed.
-------- ThreadPool Metrics ------------------------------------------------------------------------
[--] ThreadPool stat is enabled.
[--] Thread Pool Size: 8 thread(s).
[--] Using default value is good enough for your version (10.0.30-MariaDB)
-------- MyISAM Metrics ----------------------------------------------------------------------------
[!!] Key buffer used: 23.1% (992M used / 4B cache)
[OK] Key buffer size / total MyISAM indexes: 4.0G/3.5G
[OK] Read Key buffer hit rate: 100.0% (1B cached / 200K reads)
[!!] Write Key buffer hit rate: 83.2% (76K cached / 63K writes)
-------- InnoDB Metrics ----------------------------------------------------------------------------
[--] InnoDB is enabled.
[--] InnoDB Thread Concurrency: 12
[OK] InnoDB File per table is activated
[OK] InnoDB buffer pool / data size: 4.0G/480.0K
[!!] Ratio InnoDB log file size / InnoDB Buffer pool size (2.34375 %): 48.0M * 2/4.0G should be equal 25%
[!!] InnoDB buffer pool instances: 8
[--] InnoDB Buffer Pool Chunk Size not used or defined in your version
[OK] InnoDB Read buffer efficiency: 94.55% (8648 hits/ 9146 total)
[!!] InnoDB Write Log efficiency: 0% (1 hits/ 0 total)
[OK] InnoDB log waits: 0.00% (0 waits / 1 writes)
-------- AriaDB Metrics ----------------------------------------------------------------------------
[--] AriaDB is enabled.
[OK] Aria pagecache size / total Aria indexes: 128.0M/1B
[!!] Aria pagecache hit rate: 0.0% (4 cached / 4 reads)
-------- TokuDB Metrics ----------------------------------------------------------------------------
[--] TokuDB is disabled.
-------- XtraDB Metrics ----------------------------------------------------------------------------
[--] XtraDB is disabled.
-------- RocksDB Metrics ---------------------------------------------------------------------------
[--] RocksDB is disabled.
-------- Spider Metrics ----------------------------------------------------------------------------
[--] Spider is disabled.
-------- Connect Metrics ---------------------------------------------------------------------------
[--] Connect is disabled.
-------- Galera Metrics ----------------------------------------------------------------------------
[--] Galera is disabled.
-------- Replication Metrics -----------------------------------------------------------------------
[--] Galera Synchronous replication: NO
[--] No replication slave(s) for this server.
[--] This is a standalone server.
-------- Recommendations ---------------------------------------------------------------------------
General recommendations:
Control warning line(s) into /var/lib/mysql/xx.xx.com.err file
Control error line(s) into /var/lib/mysql/xx.xx.com.err file
MySQL started within last 24 hours - recommendations may be inaccurate
Reduce your overall MySQL memory footprint for system stability
Dedicate this server to your database for highest performance.
Temporary table size is already large - reduce result set size
Reduce your SELECT DISTINCT queries without LIMIT clauses
Performance should be activated for better diagnostics
Consider installing Sys schema from https://github.com/mysql/mysql-sys
Variables to adjust:
*** MySQL's maximum memory usage is dangerously high ***
*** Add RAM before increasing MySQL buffer variables ***
query_cache_type (=0)
performance_schema = ON enable PFS
innodb_log_file_size * innodb_log_files_in_group should be equals to 1/4 of buffer pool size (=2G) if possible.
innodb_buffer_pool_instances(=4)
我可以更改my.cnf以防止服务器挂起吗？
答案 0 :(得分：2)
高CPU使用率 - ＆gt;索引不足和/或查询写得不好。期。讨论结束。因此，请向我们展示查询和SHOW CREATE TABLE。
哦，有些东西会伤害CPU：
query_cache_size=2084M -- No more than 50M !
当发生任何写入时，将清除修改后的表的QC中的所有条目。质量控制越大，这就越贵。
如果您完全使用InnoDB，请更改此：
innodb_buffer_pool_size=4G -- to 30G
太大了：
max_connections=100000 -- drop to 1000
tmp_table_size=5042M -- 400M
thread_cache_size=2042M -- 10 is usually sufficient
OUCH !!这是20亿条目，而不是2GB！把它放到平原10 !!
我退出了。删除您所做的所有更改，然后添加一个更改：
innodb_buffer_pool_size=4G -- to 30G
这会让你摆脱困境。然后我们可以讨论最慢的查询。